The programme will be screened at an Amnesty International event at the UN Human Rights Council in Geneva this Friday, before it airs on Channel 4 on June 14.

Presented by Channel 4 News anchor Jon Snow, Sri Lanka's Killing Fields features footage of alleged atrocities committed by the Sri Lankan government forces and Tamil Tigers at the end of the civil war.

The UN Special Rapporteur has said that the footage, first aired on Channel 4 News last December, should be used in an international investigation of the abuses.

Channel 4's head of news and current affairs Dorothy Byrne said that the footage in Sri Lanka's Killing Fields is "probably the most horrific the channel has ever shown".

She added: "The decision to show it at length was made only after serious and careful consideration. It is of the greatest possible public interest and as such we have a duty to journalistically scrutinise it."

Last December, the Sri Lankan government banned the BBC for a third time from reporting on an official panel's investigation into alleged abuses in the country's civil war.